Physics of Tricking Part 1

[Josharoo]

Good day amigos. Below you will find a compressed document, the first in (possibly) a series on the physics of tricking. The purpose of this doc is to provide some insight into tricking practice from the scientific perspective. For those of you who are willing to read through the following 2 pages, you may learn a thing or two which will help you understand the physics behind the movements you're doing.

If nothing else, I recommend reading through the sections on rotation, torque and moment of inertia. For those of you who are unfamiliar with these terms, they may prove very enlightening.

Don't be intimidated by the equations. They're all relatively simple, and I try to explain everything as thoroughly as possible without being long-winded. If you have any questions about anything you can always just ask and I'll be glad to clarify. Enjoy!

714

[one eighty seven]

I like it.

[WilliamT]

aha, why thank you.
I was familiar with most of this, but it was still a good read nonetheless. Although there was one thing that stuck out to me. the T = F*d formula in relation to gaining momentum during cheat kick setups. I usually do this but I wasnt aware of the forumla behind it, so it was cool to learn about that, and I think i should apply it to my nines a bit more.

Thanks for writing this up, I'm interested in tricking theory and I'm hoping for a part 2

[NoMore]

NICE, really
please write more about strength to weight ratio

[Skilzat85X]

This article is awesome, good freaking job. :good:

[chicanerous]

please write more about strength to weight ratio
There's not much more to it. In the end, it's just a ratio.

Physics doesn't offer any more reasonable explanation on how to maximize relative strength than what you'll find in the guides in the Training and Conditioning forum. Training-wise it's entirely summed up by f=ma. Move masses with varying accelerations to control the force your muscles exert.

If you want strength, you lift very heavy things. If you want power, you lift heavy things as fast as possible. If you want progress, you provide a manageable stimulus that outperforms previous ones. If you want to control your bodyweight, you restrict your caloric intake.

Very basic physics explains the rationale behind these things (with the exception of that third one), but does not explain why it works. To learn that, instead, you have to look at the very complex biological and chemical processes of the body.

[Diz2007]

Great! I like the fact that the physics of tricking's concept is deep but the way you explain everything is easy to understand for anyone who's not too familiar with physics(me).What are the physics to weightlifting?I'll give you an example of what I mean,the friends I train with frequently put the fact that I'm stronger than them down to I'm smaller & therefore I have less distance to cover e.g. in squats.But...Isn't it the same range of motion?Because no matter how tall or small you are if you squat with your thighs parallel to the floor the range of motion is still what...90degrees?I wondered if I could prove them wrong?I'm a 5,6 ectomorph & my friends I train with are all around 6foot with mesomorph body types with the exception of one who's about 6,5 ectomorph.

Edit:Oh and if body weight needs to be added into the equation then I weight 140pounds the tall ectomorph also weighs about this and is significantly weaker than me & the other three mesomorphs are about 154 to about 172pounds.:smile:I'll wait for part two for you to expand on that.:good:

[Mr.Parafuso]

Very well done!

[chicanerous]

What are the physics to weightlifting?I'll give you an example of what I mean,the friends I train with frequently put the fact that I'm stronger than them down to I'm smaller & therefore I have less distance to cover e.g. in squats.But...Isn't it the same range of motion?Because no matter how tall or small you are if you squat with your thighs parallel to the floor the range of motion is still what...90degrees?I wondered if I could prove them wrong?I'm a 5,6 ectomorph & my friends I train with are all around 6foot with mesomorph body types with the exception of one who's about 6,5 ectomorph.

Edit:Oh and if body weight needs to be added into the equation then I weight 140pounds the tall ectomorph also weighs about this and is significantly weaker than me & the other three mesomorphs are about 154 to about 172pounds.:smile:I'll wait for part two for you to expand on that.:good:
Why does that matter? Comparing between between people, especially on something as unchangeable as skeletal structure, has no bearing on your own performance, which is what you should be concerned about.

Anyways, the answer stems from the fact that work is defined as force over distance. Even, if the joint angle is the same, the variation in limb lengths creates a variation in the distance that must be traveled to get there.

While in practice it's a bit more complicated, you can think of it in terms of similar 45-45-90 degree triangles. If you change the length of the sides, the hypotenuse responds accordingly -- the larger the sides, the greater the hypotenuse and vice versa.

715

Because it takes more work to reach the same angle, a taller person must expend more effort than a shorter person. However, this is mitigated by the fact that taller people have larger bones and so the muscles are correspondingly larger. This means that the taller person has a potential for much greater absolute strength than the shorter person, but the shorter person has lever advantages that can facilitate a high degree of relative strength.

This really isn't Physics, BTW. It's biomechanics / kinesiology.

[Yuri]

hmm not bad, was pretty well written

[Sakanem]

Sounds like a good read, I'll get down to it as soon as I find some time :good:

[Josharoo]

Thanks for the positive feedback guys. I will probably make a part 2 in a couple of weeks, once i get back from spring break.

In response to the weightlifting question:
If you and your friend are approximately the same strength but you are shorter you will have a definite advantage in squats (or any weightlifting practice that involves pulling weights away from the floor). The reason is that you simply don't have to lift the weight as high, which means less work output.

The equation for mechanical (physically-actuated) work is W = F * d
where F is the force you need to lift the weight (which would just be equal to the weight of the barbell), and d is the overall vertical height you lift it. So if you can both lift the same weight but you're shorter, you won't have to output as much work as your friend to get it to your max height.

Note that this power is generated as a result of chemical energy inside your body, so you will also burn less energy than your friend in the process (all else being equal).

[Nomad]

Nice read, especially since I have an interest in physics.

Now comes the question. Could you explain the physics of stalling rotation? I haven't had physics as a subject in about 4 years now, so I'm a bit rusty, but my (rather random) thoughts on it draw me to an analogy of, say, a spring. Meaning the object wants to rotate, but is not allowed to, and therefore collects potential energy, therefore increasing the speed of rotation when you let go.

Am I wrong in my presumption that stalling before a flip would actually increase the speed of rotation to a degree, or am I wrong?

[Yuri]

Nice read, especially since I have an interest in physics.

Now comes the question. Could you explain the physics of stalling rotation? I haven't had physics as a subject in about 4 years now, so I'm a bit rusty, but my (rather random) thoughts on it draw me to an analogy of, say, a spring. Meaning the object wants to rotate, but is not allowed to, and therefore collects potential energy, therefore increasing the speed of rotation when you let go.

Am I wrong in my presumption that stalling before a flip would actually increase the speed of rotation to a degree, or am I wrong?

in stalling the rotation comes from the tuck, but there is still some type of initial lean regardless of how small it is. It does not make the tuck faster, it just appears that way because of the delay. If you look at people stalling they are not completely vertical, and the longer they stall the more they end up leaning.
what makes the rotation faster is the power and size of the tuck. The harder and smaller you tuck the faster you rotate.

[Dragonfly]

Ahhh, good read, I even understood it too ^^

[Nomad]

I know the rotation comes from the tuck, because it lessens the distance between the center of rotation and the point farthest away from it, hence the same amount of rotational force is applied to an object with a smaller diameter.

What I meant is that, since you have the inertia, but are restraining it (say, when stalling a front tuck), would that not produce more potential energy?

And btw, I am not defending my statement, since it was a question to begin with. =D
The question was simply the by-product of my long time away from actively doing physics.

[Yuri]

What I meant is that, since you have the inertia, but are restraining it (say, when stalling a front tuck), would that not produce more potential energy?


I suppose if you are completely stretched out before you tuck you will have more rotational potential energy, but this is just a matter of setting properly because even stalling you are performing a small amount of rotation.

[GriffinHeart]

in stalling the rotation comes from the tuck, but there is still some type of initial lean regardless of how small it is. It does not make the tuck faster, it just appears that way because of the delay. If you look at people stalling they are not completely vertical, and the longer they stall the more they end up leaning.
what makes the rotation faster is the power and size of the tuck. The harder and smaller you tuck the faster you rotate.

i'm sorry but i think this needs a bit of a correction,

most of you said is true but some things need to be cleared. i'll try to explain the best i can while keeping stuff in the physics

why do we stall?

well from the physics point of view, when you do a backflip you have to decompose it to analize each part.

so first, we have the jump, we jump so we can gain height, when we jump we produce energy/momentum, ie we are making something move.

while jumping you have the force you applyed by the jump going upwards and the gravity going downwards, thats why we can't get to the moon by jumping =P. So there will be a moment where we will stop going up cause of gravity.
(for the sake of simplicity im omiting some other forces like frictions and etc.)

first part done if we want to do a blackflip we jump what then after?

the tuck.

In physics how do we explain the rotation of something? well the most simple way to put it is adding angular momentum to that object. one way of doing that is to tuck. it will be what makes you rotate around your center of gravity.

I won't go into any further detail in this since its not the point.

so now...where does stalling comes in the midlle of this?

the usual way to put it is jump - stall - tuck. why?

now we have to think about "energys", we are not nuclear reactors nor we have jetpacks so we can't add energy nor lose it, only transfer it. (well kind of :P)

so we jump (produce energy) then we tuck (transfering that energy into angular momentum, ie rotation), if not all energy from the jump is transfered of course you will still be going upwards while you rotate, but since our energy is very limited and we can't do that very well, thats what trampolins and stuff are for :P.

during this process energy is lost (transfered to stuff that do not help you)

how do you overcome that?

you maximize your height (all that jumping energy) and then transfer the most you can to the rotation. that is what you can call stalling

on pratical terms? you wait till you've reached maximum height before tucking

the most simple way to explain it?


if you tuck to soon you have not reached your maximum height therefor you end up with a lower backflip.
if you tuck to late you have no energy left from the jump to transfer into angular momentum, therefor you end up banging your head on the floor


do keep in mind this is a over simplified way of explaining things for the physical point of view xD.

anyways good work on that doc, i think its important for everyone to know what the hell are we doing, or why does something happen, when we warp or tuck or anything else.

if you understand the mechanics you'll be able to tune your self up and in theory perform better =P

[Yuri]

i think we have different views of what stalling is. to me what lateef crowder does on his tucks and arabians is stalling. he goes up with a straight body and tucks on the way down making it look huge

what you described I would call setting. you can get height and tuck early because you can still be going up as you are rotating. A good example would be sessh's dub backs. Setting better will also make for a better rotation because you go from completely extended to tucked.

[Josharoo]

The question about stalling is a very good one, and I will address it in the next article. I plan to do the next one on blocking, stalling, and a bit more on tucking.

Briefly, stalling doesn't increase your rotational speed, at least not directly. If you think about it, any rotational momentum you have at takeoff will be conserved while you're in the air. In other words, if you're rotating at takeoff, you'll continue rotating in the air since there's no force acting on you to stop it.

That being said, usually when you stall you also change your body configuration slightly. For example, when I stall before a front flip i tend to arch my back a little bit (leaning my upper body backwards). Though it's almost imperceptible visually, it provides extra room for the rotation during the tuck, and also gets a little swinging motion started, and consequently the rotation ends up being faster.

[Nomad]

So I was right, but with wrong reasoning. Thanks for clearing that up, guys. Looking forward to the next installment of the doc.

[kamesennin]

This is great! Im finishing my first year on Sport Science this spring and are moving on to Sport Biology (biomechanics, anatomy, fysiology etc.) for 2 more years. I was planning to do something like this myself when I had the time! Great work!

Looking forward to your articles about blocking!

[J540lover]

Awesome. I'm taking physics at school this year, so you just potentially helped me with tricking, and my education. Great writeup :wink:

[mm tacos rock]

From what I understand, tricking works like this:

I love my arms and legs and shit happens.

the mathematical equation for that is

a(90x) = s
l

[Skilzat85X]

To be honest, "stalling" is bs. At least, when it comes to actually WAITING or delaying something.

I think many people confuse the term stalling for "properly timing technique."

Example:
If you tuck before you have completed the motion of the jump, in this case extend your legs and pushing them through the ground, you will loose height. Why? Because the full jumping motion was not completed, thus the power from the motion is now minimal.

However, if you tuck as soon as your feet have left the ground and the jumping motion is complete, you will not loose height, because the motion, you legs extending and all that) is now complete, and you have no more forces pushing you up.

If you finish the jumping motion, then wait a long time to tuck, you're not going to magically get more height. In fact, you'll probably land with your chest lower.

The point is: as soon as the motion of the jump is complete, and you are no longer in contact with ground, there is NO other force that will push you up higher, and no force that will push you down, except gravity of course. And this is all provided you don't hit anything.

You don't need to wait until you "reach your maximum height", you need to wait until you've exerted your maximum upwards power.

[Tocano]

This is why the stall works, according to me (not necessarily true).

When you initiate the spin, you cut off your upwards momentum. Before the tuck, you are very aerodynamic and there is very little air resistance. When you tuck, you become a ball or a worse shape, which is resisted by air much more. Therefore you are losing height due to air resistance. When you stall, you don't waste any upwards momentum because you wait til you are at the peak of the jump to tuck.

What I don't understand is how you can initiate rotation when there are no external forces. It seems like if you brought your knees to your chest, your chest would come to your knees an equal amount and there would be no rotation. Why is it that you can bring your lower body up while keeping your upper body still.

I think I need to go do some backflip experiments...

[Yuri]

This is why the stall works, according to me (not necessarily true).

When you initiate the spin, you cut off your upwards momentum. Before the tuck, you are very aerodynamic and there is very little air resistance. When you tuck, you become a ball or a worse shape, which is resisted by air much more. Therefore you are losing height due to air resistance. When you stall, you don't waste any upwards momentum because you wait til you are at the peak of the jump to tuck.

What I don't understand is how you can initiate rotation when there are no external forces. It seems like if you brought your knees to your chest, your chest would come to your knees an equal amount and there would be no rotation. Why is it that you can bring your lower body up while keeping your upper body still.

I think I need to go do some backflip experiments...

Unless there is a hurricane in the area you are flipping, air resistance can be neglected. Either going up or tucking you are not going fast enough to make a noticeable difference. For our purposes you may as well be flipping in a vacuum.

and for your second thought, you just stated the difference between a tuck and a tuck jump. In a tuck you have some kind of initial rotation, look at anyone's tuck. No one jumps completely vertical before they tuck, there is always some type of upper body lean regardless of how small it is. This means there is an initial rotation and when the tuck happens the moment of inertia becomes smaller thus increasing rotation speed to conserve angular momentum.
In a tuck jump you jump either straight or with your chest down so there is no initial rotation.

[Rudy]

i liked it, keep 'em coming

[Ryoda]

How in the name of physics does pumping give you so much POWER?!

[Yuri]

pumping changes your moment of inertia

[chicanerous]

It seems like if you brought your knees to your chest, your chest would come to your knees an equal amount and there would be no rotation. Why is it that you can bring your lower body up while keeping your upper body still.
Hang from a bar. Now pull your knees up to your chest. Viola! You just brought your lower body up while keeping your upper body still.

Better yet, stand up. Lift one knee up. You just brought that leg to your chest. If the floor dropped out from under you, you would still be able to pull that other leg up to match the one already at your chest.

In neither case did your chest irrationally pull itself down to meet your legs.

[AjStyles]

YOU talk about mass and weight
i want to get straight to the point
generally more weight = bad for tricking??????????

[Yuri]

YOU talk about mass and weight
i want to get straight to the point
generally more weight = bad for tricking??????????


I will quote gaz by saying "body type is either a blessing or a hindrance but by no means a barrier"

generally a lot of trickers are really skinny

but you can trick regardless of your mass

it is not the magnitude of your mass that matters but how you handle your own weight

[Origional]

I love you

[540Ninja]

To be honest, "stalling" is bs. At least, when it comes to actually WAITING or delaying something.

I think many people confuse the term stalling for "properly timing technique."

Example:
If you tuck before you have completed the motion of the jump, in this case extend your legs and pushing them through the ground, you will loose height. Why? Because the full jumping motion was not completed, thus the power from the motion is now minimal.

However, if you tuck as soon as your feet have left the ground and the jumping motion is complete, you will not loose height, because the motion, you legs extending and all that) is now complete, and you have no more forces pushing you up.

If you finish the jumping motion, then wait a long time to tuck, you're not going to magically get more height. In fact, you'll probably land with your chest lower.

The point is: as soon as the motion of the jump is complete, and you are no longer in contact with ground, there is NO other force that will push you up higher, and no force that will push you down, except gravity of course. And this is all provided you don't hit anything.

You don't need to wait until you "reach your maximum height", you need to wait until you've exerted your maximum upwards power.

This is kind of how I see it. You made a good point on how stalling is bs. I think stalling is more visual than it is an actual phenomenon. You are not actually pausing the rotation, it just may seem that way in a front flip for example. I haven't studied physics very in depth, but this is just my take on it.:juji:

[Scalco]

Very good read. ^_^
I liked it

[NinjabunnyTNB]

I will quote gaz by saying "body type is either a blessing or a hindrance but by no means a barrier"

generally a lot of trickers are really skinny

but you can trick regardless of your mass

it is not the magnitude of your mass that matters but how you handle your own weight
True, but from a pure physics standpoint, more mass = more inertia, with inertia being an objects resistance to a change in its state of motion. So unless that added mass is fast twitch muscle that's been trained for tricks, it's not beneficial to have.

[mchitti]

I appreciate the idea, and effort going into this, but it's just useless... there are so many factors to take into account, it is better to judge what body is best for tricking by watching trickers, and even then, people are born with different muscle twitch type ratios.

as for skilzat, what he said is 100% true, quit saying stall, it's about setting and timing.

oh, and don't bother trying to apply maths to tricking please....

interesting topic none the less.

[Butteroll]

oh, and don't bother trying to apply maths to tricking please....

haha...too late on that one buddy.

I think this is an interesting topic, for those that want to go deeper into the physics of human motion and how it all relates to tricking, it's great. I for one would love to see more.
Thanks.

[eddy wang]

Interesting, and good to be read, i'm waiting for the part 2